/*
 * Copyright 2011,2012 Metamarkets Group Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.metamx.common.collect;


import com.google.common.base.Preconditions;
import com.google.common.collect.Iterators;

import java.lang.Iterable;
import java.util.LinkedHashMap;
import java.util.Iterator;
import java.util.Map;

public class Utils
{
  public static <K, V> Map<K, V> zipMap(K[] keys, V[] values) {
    Preconditions.checkArgument(values.length == keys.length,
                                "number of values[%s] different than number of keys[%s]",
                                values.length, keys.length);

    return zipMapPartial(keys, values);
  }
  
  public static <K, V> Map<K, V> zipMapPartial(K[] keys, V[] values)
  {
    Preconditions.checkArgument(values.length <= keys.length,
                                "number of values[%s] exceeds number of keys[%s]",
                                values.length, keys.length);

    Map<K, V> retVal = new LinkedHashMap<>();

    for(int i = 0; i < values.length; ++i) retVal.put(keys[i], values[i]);

    return retVal;
  }

  /** Create a Map from iterables of keys and values. Will throw an exception if there are more keys than values,
   *  or more values than keys. */
  public static <K, V> Map<K, V> zipMap(Iterable<K> keys, Iterable<V> values) {
    Map<K, V> retVal = new LinkedHashMap<>();

    Iterator<K> keysIter = keys.iterator();
    Iterator<V> valsIter = values.iterator();

    while (keysIter.hasNext()) {
      final K key = keysIter.next();

      Preconditions.checkArgument(valsIter.hasNext(),
                                  "number of values[%s] less than number of keys, broke on key[%s]",
                                  retVal.size(), key);

      retVal.put(key, valsIter.next());
    }

    Preconditions.checkArgument(!valsIter.hasNext(),
                                "number of values[%s] exceeds number of keys[%s]",
                                retVal.size() + Iterators.size(valsIter), retVal.size());

    return retVal;
  }

  /** Create a Map from iterables of keys and values. If there are more keys than values, or more values than keys,
    * the excess will be omitted. */
  public static <K, V> Map<K, V> zipMapPartial(Iterable<K> keys, Iterable<V> values)
  {
    Map<K, V> retVal = new LinkedHashMap<>();

    Iterator<K> keysIter = keys.iterator();
    Iterator<V> valsIter = values.iterator();

    while (keysIter.hasNext()) {
      final K key = keysIter.next();

      if(valsIter.hasNext()) retVal.put(key, valsIter.next());
      else break;
    }

    return retVal;
  }
}
